1.\" $OpenBSD: diskmap.4,v 1.3 2015/09/10 17:55:21 schwarze Exp $ 2.\" 3.\" Copyright (c) 2010 Joel Sing <jsing@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: September 10 2015 $ 18.Dt DISKMAP 4 19.Os 20.Sh NAME 21.Nm diskmap 22.Nd disklabel UID mapping interface 23.Sh SYNOPSIS 24.In sys/dkio.h 25.Sh DESCRIPTION 26The 27.Nm 28driver provides userland applications with a means to map a disklabel UID to 29an actual device and open that device in one atomic operation. 30This is achieved via the DIOCMAP 31.Xr ioctl 2 32command. 33.Pp 34The ability to use a disklabel UID is helpful in situations 35where a disk may appear to the operating system under different device names. 36For example, 37plugging USB keys into differently configured systems (think sd0 or sd1), 38or swapping between IDE and AHCI on a disk controller (wd0 or sd0). 39Although the device names may change, 40the operating system is still able to identify the disk by its UID. 41.Sh FILES 42.Bl -tag -width /dev/diskmap -compact 43.It Pa /dev/diskmap 44diskmap device 45.El 46.Sh SEE ALSO 47.Xr ioctl 2 , 48.Xr disklabel 8 49.Sh HISTORY 50The 51.Nm 52driver first appeared in 53.Ox 4.8 . 54.Sh AUTHORS 55The 56.Nm 57driver was written by 58.An Joel Sing . 59